CA1084506A - Preparation of 2,3,5-trichloropyridine - Google Patents
Preparation of 2,3,5-trichloropyridineInfo
- Publication number
- CA1084506A CA1084506A CA308,458A CA308458A CA1084506A CA 1084506 A CA1084506 A CA 1084506A CA 308458 A CA308458 A CA 308458A CA 1084506 A CA1084506 A CA 1084506A
- Authority
- CA
- Canada
- Prior art keywords
- trichloropyridine
- mixture
- reaction
- grams
- pyridine
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/61—Halogen atoms or nitro radicals
Abstract
ABSTRACT
2,3,5-Trichloropyridine is prepared by the reaction of pentachloropyridine or 2,3,5,6-tetrachloro-pyridine with metallic zinc in the presence of a strongly alkaline aqueous solution and a water-immiscible reaction medium.
2,3,5-Trichloropyridine is prepared by the reaction of pentachloropyridine or 2,3,5,6-tetrachloro-pyridine with metallic zinc in the presence of a strongly alkaline aqueous solution and a water-immiscible reaction medium.
Description
` :~
~8~5~6 PPEPARATION OF 2,3,5-TRICHLOROPYRIDINE
--1-- :
This invention relates to a process for preparing
~8~5~6 PPEPARATION OF 2,3,5-TRICHLOROPYRIDINE
--1-- :
This invention relates to a process for preparing
2,3,5-trichloropyridine.
2,3,5-T~ichloropyridlne is a known compound. It is a crystalline material melting at 48-48.5C.
2,3,5-Trichloropyridine is useful as an intermediate for prepari~g various compounds having pesticidal activity.
For example, the trichloro compound can be treated with an alkali metal hydroxide employing conventional techniques to prepare 3,5-dichloro-2-pyridinol. The pyridinol can then be reacted with a phosphorochloridate or phosphorochloridothioate to prepare toxicants useful for the control of mite, insect, bacterial and fungal organisms as taught in U.S. Patent 15 3,244,586.
2,3,5 Trichloropyridine can be prepared by a variety of methods. Sell, et al., teach reacting pyridine and phosphorus pentachloride in a sealed tube at 210-22~C, 20 J. Chem. Soc. 73, 437 tl888). Sell, J. Chem. Soc. 93, 437 (1908) suggests the chlorination of pyridine hydrochloride with chlorine gas at 115-120C for an extended period o~ time.
In a related procesq, pyridine hydrochloride is treated with liauid chlorine at 80-225C and an HCl pressure above 30 psig (3 at~ospheres absolute) as taught in U.S. Patent
2,3,5-T~ichloropyridlne is a known compound. It is a crystalline material melting at 48-48.5C.
2,3,5-Trichloropyridine is useful as an intermediate for prepari~g various compounds having pesticidal activity.
For example, the trichloro compound can be treated with an alkali metal hydroxide employing conventional techniques to prepare 3,5-dichloro-2-pyridinol. The pyridinol can then be reacted with a phosphorochloridate or phosphorochloridothioate to prepare toxicants useful for the control of mite, insect, bacterial and fungal organisms as taught in U.S. Patent 15 3,244,586.
2,3,5 Trichloropyridine can be prepared by a variety of methods. Sell, et al., teach reacting pyridine and phosphorus pentachloride in a sealed tube at 210-22~C, 20 J. Chem. Soc. 73, 437 tl888). Sell, J. Chem. Soc. 93, 437 (1908) suggests the chlorination of pyridine hydrochloride with chlorine gas at 115-120C for an extended period o~ time.
In a related procesq, pyridine hydrochloride is treated with liauid chlorine at 80-225C and an HCl pressure above 30 psig (3 at~ospheres absolute) as taught in U.S. Patent
3,732,230.
18,391-F
~ ' ~ .
The above prior art methods are useful for the preparation of 2,3,5-trichloropyridine in small yields on a laboratory scale, but these methods are too expensive to be carried out on a commercial scale. Therefore, a more practical process is sought.
The present invention provides a process for preparing 2,3,5-trichloropyridine which comprises reacting at a pH of 11 or above and at a temperature of from 20 to 100C, a pyridine reactant selected from 2,3,5,6-tetra-chloropyridine and pentachloropyridine with from 1 to 3 gram atoms of zinc per gram atom of chlorine to be removed, in the presence of an alkaline reagent and a water-immiscible reaction medium.
By this process, 2,3,5-trichloropyridine of high purity and in high yield can be obtained.
In carrying out the process of the present inven-tion, the 2,3,5,6-tetrachloropyridine or pentachloropyridine reactant is mixed with the reaction medium and sufficient alkaline reagent to maintain the mixture at a pH of at least 11, preferably 12 to 14, and metallic zinc. The reaction is generally complete in from 1 to 120 hours. The tempera-ture employed is most conveniently the reflux temperatureof the mixture. The metallic zinc or alkaline reagent can be added to the mixture either before or after the mixture is brought to the reaction temperature. The sequence of addition of the reactants is not critical.
~ lthough the zinc reacts to remove chlorine in an equimolar relationship, it~is preferred that excess zinc be employed to ensure completion of the reaction. The zinc is, therefore, èmployed in a ratio of from l to 3 gram atoms of zinc per gram atom of chlorine to be removed.
.
18~39l-F
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5(~6 It is important to carry out the reaction in the presence of a strongl~ alkaline medium with the reaction mixture being at p~ of at least 11, since at a lower pH, tetrachloropyridine is mors readily reduced to the dichloro-pyridine, reducing the yield of the desired 2,3,5-trichloro-pyridine.
At the completion of the reaction, the reaction mixture is cooled and, with or without dilution with water, filtered to remove any unreacted zinc and other by-products.
The filter cake is washed with ~ solvent such as, for example, toluene or benzene to extract any product adhering thereto.
~he solvent can, if desired, be added to the reaction ~ixture before filtration. The solvent is thereafter removed by evaporation. The product can be further purified, if desired, by fractional distillation or other conventional techniques.
Representative water-immiscible solvents which can be employed in the present invention include, for example, xylene, toluene, benzene, hexane, heptane, ethylbenzene, and anisole.
Representative alkaline reagents for use in the present invention include ethylene diamine, triethylamine, ammonium, hydroxide, and the hydroxides of sodium, potassium, lithium, cesium and rubidium.
The following examples illustrate the present invention.
Example 1 ~nto a 5-liter, fluted, 3-neck flask which was fitted with a reflux condenser, a heater, thermometer, and mechanical stirrer, was ~dded 251 grams (1.0 mole) of penta-35 chloropyridine, 500 milliliters of toluene, and 1.25 liters 18,391-F
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. : . . :
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18,391-F
~ ' ~ .
The above prior art methods are useful for the preparation of 2,3,5-trichloropyridine in small yields on a laboratory scale, but these methods are too expensive to be carried out on a commercial scale. Therefore, a more practical process is sought.
The present invention provides a process for preparing 2,3,5-trichloropyridine which comprises reacting at a pH of 11 or above and at a temperature of from 20 to 100C, a pyridine reactant selected from 2,3,5,6-tetra-chloropyridine and pentachloropyridine with from 1 to 3 gram atoms of zinc per gram atom of chlorine to be removed, in the presence of an alkaline reagent and a water-immiscible reaction medium.
By this process, 2,3,5-trichloropyridine of high purity and in high yield can be obtained.
In carrying out the process of the present inven-tion, the 2,3,5,6-tetrachloropyridine or pentachloropyridine reactant is mixed with the reaction medium and sufficient alkaline reagent to maintain the mixture at a pH of at least 11, preferably 12 to 14, and metallic zinc. The reaction is generally complete in from 1 to 120 hours. The tempera-ture employed is most conveniently the reflux temperatureof the mixture. The metallic zinc or alkaline reagent can be added to the mixture either before or after the mixture is brought to the reaction temperature. The sequence of addition of the reactants is not critical.
~ lthough the zinc reacts to remove chlorine in an equimolar relationship, it~is preferred that excess zinc be employed to ensure completion of the reaction. The zinc is, therefore, èmployed in a ratio of from l to 3 gram atoms of zinc per gram atom of chlorine to be removed.
.
18~39l-F
~ .
. ' - ' ~ .
~. .. ~ . . : .: . . . . . . ~
5(~6 It is important to carry out the reaction in the presence of a strongl~ alkaline medium with the reaction mixture being at p~ of at least 11, since at a lower pH, tetrachloropyridine is mors readily reduced to the dichloro-pyridine, reducing the yield of the desired 2,3,5-trichloro-pyridine.
At the completion of the reaction, the reaction mixture is cooled and, with or without dilution with water, filtered to remove any unreacted zinc and other by-products.
The filter cake is washed with ~ solvent such as, for example, toluene or benzene to extract any product adhering thereto.
~he solvent can, if desired, be added to the reaction ~ixture before filtration. The solvent is thereafter removed by evaporation. The product can be further purified, if desired, by fractional distillation or other conventional techniques.
Representative water-immiscible solvents which can be employed in the present invention include, for example, xylene, toluene, benzene, hexane, heptane, ethylbenzene, and anisole.
Representative alkaline reagents for use in the present invention include ethylene diamine, triethylamine, ammonium, hydroxide, and the hydroxides of sodium, potassium, lithium, cesium and rubidium.
The following examples illustrate the present invention.
Example 1 ~nto a 5-liter, fluted, 3-neck flask which was fitted with a reflux condenser, a heater, thermometer, and mechanical stirrer, was ~dded 251 grams (1.0 mole) of penta-35 chloropyridine, 500 milliliters of toluene, and 1.25 liters 18,391-F
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. : . . :
. . . . . . .. . . .. . . .
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-4-of 8N sodium hydroxide. The mixture was heated to 90C, with stirring, and 260 grams (4.0 gram atoms) of zinc dust was added thereto, and the mixture was thereafter refluxed for 2.75 hours. The pH of the mixture was 14-15. The re-action mixture was cooled to room temperature and filtered to remove insolubles. The filter cake was washed with toluene and the toluene wash combined with the reaction mixture filtrate. The toluene was removed. Fractional distillation of the mixture yielded 126 grams of a colorless liquid boil-ing at 105-115C at 30 mm.Hg which consisted of about 92 percent 2,3,5-trichloropyridine. Recrystallization of the product from hexane, with cooling to -20C gave 80 grams of crystalline product of 93+ percent purity. The product melted at 47-48C and was found upon analysis to ha~e carbon, hydrogen and nitrogen contents of 32.9, 1.2 and 7.8 percent, respectively, as compared with the theoretical contents of 32.9, 1.2 and 7.7 percent, respectively.
Example 2 To a 500 milliliter, 3-neck flask, which was fitted with a reflux condenser, heater, thermometer, and stirrer, was added 200 milliliters (1.2 moles) of 6N anmonium hydroxide, 39.0 grams (0.60 gram atom) of zinc dust, 100 milliliters of toluene, and 25.1 grams (0.1 mole) of pentachloropyridine.
The pH of the mixture was 12.6. l'he mixture was heated to 70C, with stirring, and held under these conditions for 35 hours. At the end of this period, the reaction mixture was cooled to 20C and filtered to remove insolubles. The filter cake was washed with toluene and the toluene combined with the filtrate and concentrated by distillation. Yield of 30 2,3,5-trichloropyridine was 9.39 grams (52 percent of theoretical).
Example 3 Into a 5-liter, fluted, 3-neck flask fitted with a reflux condenser, heater, thermometer, and stirrer, was added 18,391-F
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Example 2 To a 500 milliliter, 3-neck flask, which was fitted with a reflux condenser, heater, thermometer, and stirrer, was added 200 milliliters (1.2 moles) of 6N anmonium hydroxide, 39.0 grams (0.60 gram atom) of zinc dust, 100 milliliters of toluene, and 25.1 grams (0.1 mole) of pentachloropyridine.
The pH of the mixture was 12.6. l'he mixture was heated to 70C, with stirring, and held under these conditions for 35 hours. At the end of this period, the reaction mixture was cooled to 20C and filtered to remove insolubles. The filter cake was washed with toluene and the toluene combined with the filtrate and concentrated by distillation. Yield of 30 2,3,5-trichloropyridine was 9.39 grams (52 percent of theoretical).
Example 3 Into a 5-liter, fluted, 3-neck flask fitted with a reflux condenser, heater, thermometer, and stirrer, was added 18,391-F
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5 251.0 grams (1.0 mole) of pentachloropyridine, 500 milliliters of benzene, and 1.25 liters of 8N sodium hydroxide (10 moles).
The mixture was heated to 75C, with stirring. At this time, 260.~ grams (4.0 gram atoms) of zinc dust was add~d and the mixture refluxed at about 79C for a total reaction time of 5 hours. The pH of the reaction mixture was 14-15. At the completion of the reaction, the reaction mixture was cooled to room temperature and filtered to remove insolubles. The filter cake was washed with benzene and the benzene wash was combined with the filtrate. Yield of 2,3,5-trichloropyridine was 140.9 grams (77 percent of theoretical).
~xample 4 To a 5-liter, 3-neck flask fitted with a reflux condenser, heater, thermometer, and stirrer, was added 216.9 grams (1.0 mole) of 2,3,5,6-tetrachloropyridine, 500 milli-liters of benzene, 1.0 liter of 8N sodium hydroxide, and 130.7 grams (2.0 gram atoms) of zinc dust. The pH of the mixture was 14-15, and the mixture was heated at reflux temperature, with stirring, for 7 hours. After completion of the reaction, the reaction mixture was cooled and filtered.
The filter cake was washed with benzene, and the benzene wash was combined with the filtrate. Yield of 2,3,5-trichloro-pyridine was 131.35 grams (72 percent of theoretical).
By following the above procedures, additional runs showed similar yields of the 2,3,5-trichloropyridine product.
Such additional runs, using toluene as the solvent, are set forth bslow in Table I.
18,391-F
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18, 391-F
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The mixture was heated to 75C, with stirring. At this time, 260.~ grams (4.0 gram atoms) of zinc dust was add~d and the mixture refluxed at about 79C for a total reaction time of 5 hours. The pH of the reaction mixture was 14-15. At the completion of the reaction, the reaction mixture was cooled to room temperature and filtered to remove insolubles. The filter cake was washed with benzene and the benzene wash was combined with the filtrate. Yield of 2,3,5-trichloropyridine was 140.9 grams (77 percent of theoretical).
~xample 4 To a 5-liter, 3-neck flask fitted with a reflux condenser, heater, thermometer, and stirrer, was added 216.9 grams (1.0 mole) of 2,3,5,6-tetrachloropyridine, 500 milli-liters of benzene, 1.0 liter of 8N sodium hydroxide, and 130.7 grams (2.0 gram atoms) of zinc dust. The pH of the mixture was 14-15, and the mixture was heated at reflux temperature, with stirring, for 7 hours. After completion of the reaction, the reaction mixture was cooled and filtered.
The filter cake was washed with benzene, and the benzene wash was combined with the filtrate. Yield of 2,3,5-trichloro-pyridine was 131.35 grams (72 percent of theoretical).
By following the above procedures, additional runs showed similar yields of the 2,3,5-trichloropyridine product.
Such additional runs, using toluene as the solvent, are set forth bslow in Table I.
18,391-F
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~a z z z z z z z; z ; z z z 0 OD ~ O
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18, 391-F
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Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing 2,3,5-trichloro-pyridine which comprises reacting at a pH of 11 or above and at a temperature of from 20° to 100°C, a pyridine reactant selected from 2,3,5,6-tetrachloropyridine and pentachloropyridine with from 1 to 3 gram atoms of zinc per gram atom of chlorine to be removed, in the presence of an alkaline reagent and a water-immiscible reaction medium.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US833,126 | 1977-09-14 | ||
| US05/833,126 US4111938A (en) | 1977-09-14 | 1977-09-14 | Preparation of 2,3,5-trichloropyridine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084506A true CA1084506A (en) | 1980-08-26 |
Family
ID=25263502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA308,458A Expired CA1084506A (en) | 1977-09-14 | 1978-07-31 | Preparation of 2,3,5-trichloropyridine |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US4111938A (en) |
| JP (1) | JPS601308B2 (en) |
| CA (1) | CA1084506A (en) |
| CH (1) | CH638497A5 (en) |
| DE (1) | DE2836077C2 (en) |
| ES (1) | ES473374A1 (en) |
| FR (1) | FR2403335A1 (en) |
| GB (1) | GB2004275B (en) |
| IL (1) | IL55290A0 (en) |
| IT (1) | IT1099027B (en) |
| NL (1) | NL187858C (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4242183A (en) * | 1979-04-13 | 1980-12-30 | The Dow Chemical Company | Highly active silver cathode, preparation of same and use to make 2,3,5-trichloropyridine |
| US4259495A (en) * | 1979-09-10 | 1981-03-31 | Ciba-Geigy Corporation | Process for producing 2,3,5,6-tetrachloropyridine |
| US4258194A (en) * | 1979-09-10 | 1981-03-24 | Ciba-Geigy Corporation | Process for producing 2,3,5-trichloropyridine |
| US4287347A (en) * | 1980-05-12 | 1981-09-01 | Ciba-Geigy Corporation | Process for producing 2,3,5-trichloropyridine |
| US4783536A (en) * | 1985-02-07 | 1988-11-08 | The Dow Chemical Company | Selective reduction of pentachloropyridine to 2,3,5,6-tetrachloropyridine with zinc dust in basic media |
| US4659835A (en) * | 1986-01-03 | 1987-04-21 | The Dow Chemical Company | Preparation of tetrachloropyridine |
| US6051714A (en) * | 1998-03-12 | 2000-04-18 | Reilly Industries, Inc. | Processes for dechlorinating pyridines |
| EP1098880A4 (en) * | 1998-07-15 | 2002-10-23 | Reilly Ind Inc | Dechlorination of pyridines in acidic, zinc-containing mediums |
| JP2001139551A (en) * | 1999-11-15 | 2001-05-22 | Tohkem Products Corp | Method for producing 2,3,5,6-tetrafluoropyridine |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3931190A (en) * | 1974-03-04 | 1976-01-06 | Olin Corporation | Preparation of 2-chloropyridine by hydrogenolysis |
| US3993654A (en) * | 1974-05-16 | 1976-11-23 | The Dow Chemical Company | Preparation of tetrachloropyridine |
-
1977
- 1977-09-14 US US05/833,126 patent/US4111938A/en not_active Expired - Lifetime
-
1978
- 1978-07-31 CA CA308,458A patent/CA1084506A/en not_active Expired
- 1978-08-04 IL IL7855290A patent/IL55290A0/en not_active IP Right Cessation
- 1978-08-16 NL NLAANVRAGE7808504,A patent/NL187858C/en not_active IP Right Cessation
- 1978-08-17 DE DE2836077A patent/DE2836077C2/en not_active Expired
- 1978-08-25 GB GB7834625A patent/GB2004275B/en not_active Expired
- 1978-08-31 FR FR7825148A patent/FR2403335A1/en active Granted
- 1978-09-12 IT IT27536/78A patent/IT1099027B/en active
- 1978-09-14 CH CH961278A patent/CH638497A5/en not_active IP Right Cessation
- 1978-09-14 JP JP53113510A patent/JPS601308B2/en not_active Expired
- 1978-09-14 ES ES473374A patent/ES473374A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2403335B1 (en) | 1982-07-02 |
| FR2403335A1 (en) | 1979-04-13 |
| NL187858C (en) | 1992-02-03 |
| GB2004275A (en) | 1979-03-28 |
| GB2004275B (en) | 1982-01-13 |
| JPS601308B2 (en) | 1985-01-14 |
| CH638497A5 (en) | 1983-09-30 |
| NL7808504A (en) | 1979-03-16 |
| NL187858B (en) | 1991-09-02 |
| DE2836077C2 (en) | 1986-09-11 |
| US4111938A (en) | 1978-09-05 |
| IT1099027B (en) | 1985-09-18 |
| ES473374A1 (en) | 1979-04-16 |
| IL55290A0 (en) | 1978-10-31 |
| JPS5452082A (en) | 1979-04-24 |
| DE2836077A1 (en) | 1979-03-22 |
| IT7827536A0 (en) | 1978-09-12 |
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